Besides our home , I own a condominium and some property with other investors.

I grew up in a single parent household.

The condominium project itself has to be evaluated, not simply the individual unit. 

Your household names: Ernst and Young, Deloitte, KPMG, etc all offer audit services, as do your regionals like Grant Thornton.A full audit will typically consist of spot checking everything from invoices/receipts tying out to specific checks paid by accounts payable, and down to leases being input into the system, and tying rent payments to cleared checks.  

You could have a zip code with 1000 household/house ; highest price PSF for that home lets say $1K/sqft ; $1,000,000  but 89% in that neighborhood works for USPS.

That's a valid point.The partition would be more of a temporary measure, once the back yard is developed the whole property should go into a condominium. 

The options are either the tenant pays for the damage of any of their household occupants, human or animal, or they get evicted.

There are two classifications as alluded earlier one is the property itself (used by appraisers) and one on the neighborhood.Mostly people here refer to the neighborhood.I’ve always looked at medium household income to hedge the neighborhood.

If I use my FHA loan, after a year of living in the household, can I convert my FHA to my LLC and still reap the benefits of that 3.5% down payment? 

The median household income in that zip code is $60KThat house will never rent for more than 3K on a good day.Sometimes its better to look away from estimators and look at what is actually happening.Sorry to burst your bubble, could still be a good deal.